Horizontal cuts of the modulus of the horizontal components of velocity in the domain. The cuts are taken approximately at the visible solar surface (top panels) and in the upper photosphere (bottom panels). The left panels correspond to the initial non-magnetic snapshot, while the right panels correspond to the well-developed magnetic model. Vortex motions are clearly visible in the bottom-right panel. The contours on the bottom-right panel bound the regions where the vertical component of magnetic field B_y < 30   G.